ES2811094T3 - Absorbent core without pulp and core forming method - Google Patents

Abstract

A method of forming an absorbent core, the method comprising: providing a first layer of material (12); coupling elastic yarns (14) under tension to the first material layer (12) to form a combination of elastic and material layer; performing a first stress relief to partially relax the elastic threads (14), wherein the partial relaxation of the elastic threads (14) deforms the first material layer (12) to form a plurality of valleys in the first material layer ( 12) to capture a superabsorbent polymeric material (16); applying the superabsorbent polymeric material (16) over the first material layer (12); and coupling a second material layer (20) to the combination of first material layer and elastic.

Description

DESCRIPTION

Absorbent core without pulp and core forming method

Background of the invention

The present invention relates to the formation of pulpless absorbent cores for use in disposable products such as diapers and sanitary napkins.

Sanitary napkins used in feminine hygiene are absorbent articles used by women to recover unwanted bodily discharges. These absorbent articles are typically composed of an absorbent core sandwiched between layers of woven or nonwoven materials.

Diapers generally comprise an absorbent insert or patch and a chassis, which, when the diaper is worn, supports the insert close to the wearer's body. Additionally, the diapers may include various other patches, such as tape tab patches, reusable fasteners, and the like. The raw materials used to form a representative insert are typically cellulose pulp, tissue paper, polyethylene, nonwoven web, acquisition materials, and elastics, although application specific materials are sometimes used. Typically, most insert raw materials are provided in roll form, and are unwound and applied in assembly line form.

In creating a diaper (and often also in combination with feminine hygiene products), multiple roll-fed web processes are typically used.

To create an absorbent insert, the cellulose pulp is unwound from the supplied raw material roll and pulverized by a pulp mill. Discrete pulp cores are formed by a core forming assembly and placed in a continuous web of tissue. Optionally, powder or superabsorbent polymer (SAP) can be added to the pulp core. The band of tissue is wrapped around the pulp core. The wrapped core is reduced by passing through a calendering unit, which at least partially compresses the core, thus increasing its density and structural integrity. After unpacking, the tissue-wrapped core is passed through a segregating unit or knife, in which the individual wrapped cores are cut. The cut cores are brought, with the appropriate pitch, or space, to a limit compression unit.

While the insert cores are being formed, other insert components are preparing to be presented to the limit compression unit. For example, the polyethylene sheet is prepared to receive a cut core. Like cellulose pulp, polyethylene sheet material is generally provided in roll form. The polyethylene sheet is fed through a splicer and accumulator, coated with an adhesive in a predetermined pattern, and then presented to the limit compression unit. In addition to the polyethylene sheet, which can form the bottom of the insert, a two-layer top sheet can also be formed in parallel to the formation of the core. Representative layers are an acquisition web material and a non-woven web material, both of which are fed from rolls of material, through a splicer and an accumulator. The layers are adhesive coated, bonded together, cut to size and presented to the limit compression unit. Therefore, in the limit compression unit, three components are provided for mounting: the polyethylene bottom sheet, the core, and the two-layer top sheet.

A representative limit compression unit includes a die roll and a platen roll. When all three insert components are provided to the limit compression unit, the nip of the rollers adequately compresses the insert limit. Thus, a chain of interconnected diaper inserts is provided at the exit of the limit compression unit. The diaper inserts are then separated by an insert blade assembly and properly oriented. At this point, the complete insert is ready to be placed in a diaper chassis.

A representative diaper chassis comprises nonwoven fabric material and support structure. The diaper support structure is generally elastic and can include elastic leg bands, elastic waist bands, and elastic tummy bands. The support structure is generally sandwiched between layers of the non-woven fabric material, which is fed from rolls of material, through splicers and accumulators. The chassis can also be provided with various patches, in addition to the absorbent insert. Representative patches include tape tabs and resealable zippers.

The process uses two main carrier bands; a nonwoven fabric that forms an inner liner fabric, and an outer fabric that forms an outward facing layer in the finished diaper. In a representative chassis process, the nonwoven fabric is cut at a cutting station by rotating blades along three lines, thus forming four bands. One of the lines is approximately on the center line of the band and the other two lines are parallel and a short distance apart from the center line. The effect of such a cut is to make two folds; First, to separate the non-woven web into two inner diaper liners. One liner will become the inside of the front of the diaper, and the second liner will become the inside of the back of that garment. Second Instead, two separate, relatively narrow strips are formed that can later be used to cover and trap portions of the leg hole elastics. The strips can be physically separated by an angularly disposed separator roll and laterally aligned with their downstream target positions at the inner edges of the formed liners.

After cutting the nonwoven web, an adhesive is applied to the liners in a predetermined pattern in preparation for receiving the leg hole elastic. The elastic for the leg hole is applied to the liners and then covered with the previously separated narrow strips of the non-woven band. The adhesive is applied to the outer band, which is then combined with the mounted inner bands that have elastic thereon, thus forming the chassis of the diaper. Next, after the elastic members have been positioned between the inner and outer bands, an adhesive is applied to the chassis. The chassis is now ready to receive an insert.

To assemble the final diaper product, the insert must be combined with the chassis. Placement of the insert into the chassis is done on a placement drum or on a patch applicator. The inserts are provided to the chassis on the placement drum at a desired pitch or space. The generally flat chassis / insert combination is folded so that the inner risers face each other and the combination is trimmed. A sealer bonds the bands in appropriate locations before cutting individual diapers from the folded and sealed bands.

Typically, disposable undergarments, such as pant diapers, are made up of two layers of nonwoven material with elastic threads of material placed between the two layers of nonwoven material, thus creating an elastic band laminate. The layers of material are continuous sheets of material that are eventually cut into individual lengths of undergarments. The elastic threads can be arranged and cut so that specific areas of the undergarment are free from tension or elastic forces. An absorbent pad, often contained within an insert or core, is also placed in the pant diaper product.

To ensure that the pant diaper retains a proper shape and to support all the added layers of the diaper, the backing layers and backing materials are typically added to the continuous sheets of material, with the backing layers corresponding to the elastic threads. cut from each individual preform. Each of these layers must be adhesively bonded at some point in the manufacturing process to the elastic band laminate to form the complete undergarment.

Often voids must be created in the diaper, such as holes cut from the main band for the leg holes given when the undergarment is finally formed. To create the voids, the band is typically punched, with the band sectioned between a die and an anvil. The portion of the web material that is removed is called a "chunk". As the die wears out over time, the sectioning of the piece of web material gradually turns into a duller cut. This complicates chunk removal because sectioning might not create a continuous cut chunk, possibly with some strands of web material still engaging the chunk with the web. It is desired to lengthen the amount of time and increase the number of pieces in which a die can be used effectively, to reduce the number of die changes.

Typically, the absorbent fibrous material is composed of cellulose wadding or cellulosic wood pulp material commonly referred to as "fluff", although a mixture of natural and synthetic fibers is within the scope of the invention. An absorbent core composed of wood pulp fluff is typically formed using conventional air-laying techniques.

The overall absorption of these absorbent cores has been greatly improved by the addition of superabsorbent material or superabsorbent polymer (SAP) to commonly used absorbent fibrous materials.

The ability of these absorbent cores to handle the normal surges of liquid flow is highly dependent on the proper distribution of the superabsorbent material within the absorbent fluff. When most superabsorbent materials absorb aqueous fluids, they swell substantially, often to double their dry dimensions or more at saturation. As these superabsorbent materials absorb fluid and swell, they generally become a jelly-like mass.

There has been a trend to cut down on most diapers, in attempts to make them more like underwear and take up less space on retail shelves. Generally, the thinner the diaper, the higher the concentration of superabsorbent material required to produce the same level of absorbency. High levels of superabsorbent material tend, however, to be more difficult to control and maintain in position.

In conventional core formation processes. Three-dimensional lint receiving pockets rotate around a vacuum drum. The pockets typically include baffles and screens that allow air flow through the pockets. Lint is applied to air-entrained lint reception pockets applied to pockets. The vacuum draws lint to a screen-like mesh that forms the pockets. The pockets retain the lint and the amount of lint accumulates from the screen that forms the pocket. However, some of the lint passes through the pocket screen and into the vacuum stream that draws the lint into the pocket. Therefore, some fluff is undesirably trapped in the vacuum stream.

In the conventional core forming process, it is desired to balance the amount of air that pushes the fluff into the cavity that forms the core and the amount of vacuum used to retain the fluff within the pocket. Machine processes have become more complex as the speed of the machines increases, so that the air handling systems used in this process have higher demands. For example, if the machine runs faster, the pulp is required to be delivered to the core-forming pocket faster, necessitating more airflow to the pocket. To supply more pulp to the pocket, more vacuum is required to retain the pulp within the pocket. One complication is achieving an optimal balance between the air in the pocket and the vacuum applied to the back side of the pocket.

The imbalance between the amount of pulp that supplies air to the core that forms the pocket and the vacuum applied to the back side of the pocket, retaining the fluff, causes fluff to escape forming the chamber. Conventional core-forming technology allows limited adjustability in trying to achieve the optimal balance between air and vacuum. The largest air supply comes from a fiber mill that supplies fluff and blows the fluff into the core forming chamber.

Another source of air in the forming process is the dust collection equipment, which returns the collected fluff from the vacuum stream to the core that forms the drum.

Starting with the fluff passing through the core that forms the pocket, the vacuum stream conducts the fluff within the vacuum stream to the dust collection unit. A filter inside the dust collection unit captures this lint, this lint is removed from the filter and recycled to the core formation process. Typically, this vacuum stream is fed to a drum filter housing, such as described in US Patent No. 5,679,136, the commercial embodiments of which are available from Osprey Corporation.

Pulpless kernels are a recent development. In these embodiments, an absorbent core is formed without cellulosic fibers. It is known to use SAP with pockets created in a substrate (sometimes with vacuum), but the pockets formed resist expansion with expansion of the SAP.

US 2003/120243 discloses an absorbent article comprising a liquid-impervious outer cover, a liquid-permeable body side liner superimposed on the outer cover, and a continuous elastic absorbent core, disposed between the outer cover and the liner of the side of the body.

US 2005/101929 discloses an absorbent core for a disposable absorbent article comprising a central fibrous layer and a three-dimensional underlayer having a plurality of small pockets containing superabsorbent polymer particles.

US 2006/167424 discloses a disposable absorbent article comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, and a pulpless absorbent core interposed between the topsheet and the backsheet having a superabsorbent material.

US 2006/184149 discloses an absorbent article containing a web of hydrophilic fibers and a superabsorbent polymer embedded in the web.

Summary of the invention

The present invention provides a method of forming an absorbent core according to claim 1, a stretchable absorbent core according to claim 4 and a diaper product according to claim 7.

Also described is a method and apparatus for forming an absorbent core or cores. More particularly, the cores of the present invention and the methods for forming them, reduce or eliminate absorbent fibrous material composed of cellulose wadding or cellulosic wood pulp material. The result is a pulpless core.

The method allows the ability to extend into a channel created along the machine direction if desired. Once the SAP expands, the corrugations (roughness) can be elongated and waste of SAP is avoided if the SAP is not exposed to the liquid. Waste of SAP can also be avoided by better control of SAP supply, such as gradient deposition or pattern deposition. In the current art, the acquisition / distribution layer (ADL) is responsible for all liquid distribution, but in the present invention, the core itself can even aid liquid retention, acquisition and distribution to the core.

A core with flexibility for superabsorbent expansion is provided by using stretched elastic yarns attached to a preferably non-woven layer, using elastic adhesive, for example, and then the elastic / non-woven combination is partially relaxed to create still receiving valleys. (pleats) and these are filled with SAP and then a layer of non-woven or acquisition film can be added on top of the elastic / non-woven combination carrying SAP. The nonwoven upper can be attached to the elastic / nonwoven combination, for example, by glue with core integrity adhesive.

In the present invention, the core preferably has some stretch in the machine direction or transverse machine direction, which can assist with product fit. Inextensible cores do not stretch, but the present invention provides a controlled amount and directional stretch as desired. The amount of stretch is fully adjustable to the extent that the elastic yarns are initially stretched prior to engagement with a nonwoven layer, and to the extent that the elastic / nonwoven combination is relaxed. Additionally, directional stretch or patterned stretch can be provided by changing the placement pattern of the elastic.

An absorbent core material is disclosed comprising a first layer of material; a series of elongated elastic members running in the machine direction and spaced in a transverse machine direction, said elongated elastic members coupled to said first layer of material at a first tension of said elongated elastic cord members; a superabsorbent polymeric material provided in spaces between elongated elastic members adjacent to a second tension of said elongated elastic cord members, said first tension greater than said second tension; a second layer of material coupled to said elongated elastic members; said first layer of material, said elastic members, said superabsorbent polymer and said second layer of material creating a stretchable absorbent core web. The relaxation of the elastic creates valleys or depressions in the first layer of material that can capture the superabsorbent material, and when the second layer of material is provided and coupled to the first layer of material, the stretchable absorbent core web is formed. A first zone comprising said first layer of material, said elastic members, said superabsorbent polymer and said second layer of material is described; and a second zone comprising said first layer of material directly coupled to said second layer of material, said second zone substantially free of superabsorbent polymer is described. After formation of the stretchable absorbent core web, the stretchable absorbent core web can be sectioned into discrete core portions and placed in a diaper chassis, or incorporated into a diaper product or a different type of absorbent disposable product according to is desired. The superabsorbent polymeric material may be provided intermittently in said machine direction to create a machine direction superabsorbent polymer gap, and this gap may be where said absorbent core material is sectioned into discrete core portions.

Brief description of the drawings

Figures 1a and 1b are top and side process views, respectively, of a core forming process of the present invention, with a first nonwoven web receiving a plurality of elastic yarns under tension; Figures 2a and 2b are top and side process views respectively, showing a first tension released from the elastic threads, to create peaks and valleys in the nonwoven material;

Figures 3a and 3b are top and side process views respectively, showing a SAP distribution system applying SAP placed in the peaks and valleys created in the nonwoven;

Figures 4a and 4b are top and side process views respectively, showing a second nonwoven layer applied over the elastic yarns and SAP filled peaks and valleys in the first nonwoven layer;

Figure 5 is a side view of the second non-woven layer applied over the elastic yarns and the SAP filled peaks and valleys in the first non-woven layer, showing a second tension released from the elastic yarns to create a continuous band of elastic material. absorbent core;

Figure 6 is a first alternative embodiment of an elastic yarn deposition pattern on the first nonwoven layer;

Figure 7 is a second alternative embodiment of an elastic yarn deposition pattern on the first nonwoven layer;

Figure 8 is a cross-sectional view of the second non-woven layer applied over the elastic yarns and the peaks and valleys filled with SAP in the first non-woven layer, showing a second tension released from the elastic yarns, in use conditions, for example, the shape of an absorbent core would be when a user wears a diaper;

Figure 9 is a top view of the second nonwoven layer applied over the elastic yarns and the SAP filled peaks and valleys in the first nonwoven layer, showing a second tension released from the elastic yarns to create a continuous web of elastic material. absorbent core, the absorbent core turned and placed on a web running in a receiver;

Figure 10 is a top view of a portion of a system for producing an absorbent core;

Figure 11 is a side view of the portion of the system shown in Figure 10;

Figure 12 is a side view of other parts of the system for producing an absorbent core shown in Figure 10;

Figure 13a is a bottom view of a system for applying adhesive to a nonwoven top layer for use in creating an absorbent core;

Figure 13b is a bottom view of an alternative system for applying adhesive to a nonwoven top layer for use in creating an absorbent core;

Figure 13c is a top view of a SAP delivery system applying SAP in a preferred embodiment of SAP rails to a base nonwoven layer coupled to elastic yarns;

Figure 13d is a top view of a SAP delivery system applying SAP in a second preferred embodiment of intermittent SAP lanes to a base nonwoven layer coupled to elastic yarns; Figure 14 is a side view of a roll / nip combination coupling a nonwoven top layer to elastic yarns carried by a base nonwoven layer, the base nonwoven layer carrying SAP material; Figure 15 is a cross-sectional view of a nonwoven top layer coupled to elastic yarns carried by a base nonwoven layer, the base nonwoven layer carrying SAP material to form an absorbent core laminate;

Figure 16 is a side view of a system for winding a nonwoven top layer coupled to elastic yarns carried by a base nonwoven layer, the base nonwoven layer carrying SAP material to form an absorbent core laminate;

Figure 17 is a side view of a system for stacking a nonwoven top layer coupled to elastic yarns carried by a base nonwoven layer, the base nonwoven layer carrying SAP material to form an absorbent core laminate;

Figure 18 is a perspective view of an absorbent core laminate.

Description of the preferred embodiment

While the disclosure herein is detailed and accurate to enable those skilled in the art to practice the invention, the physical embodiments disclosed herein merely exemplify the invention that can be made in other specific structures. While the preferred embodiment has been described, the details can be modified without departing from the invention.

In a preferred embodiment, the creation of an absorbent core is achieved by using two layers of nonwoven material 12 and 20, sandwiching SAP 16 and elastic yarns 14 between the two layers of nonwoven material 12 and 20. However, in Instead of one or both layers of nonwoven material 12 and 20, other materials may be used, such as woven materials, elastic materials, or any other useful material. The invention is not limited to the use of layers of nonwoven material in the creation of the laminate.

Referring now to Figures 1a and 1b, top and side process views respectively of a core forming process are shown. A first nonwoven web 12 receives a plurality of elastic yarns 14 under tension.

Referring now to Figures 2a and 2b, a first released tension of the elastic threads 14 is allowed, to create peaks and valleys (or folds) 22 in the nonwoven material 12. Referring now to Figures 3a and 3b , a SAP distribution system 19 applies placed SAP 16 to the created peaks and valleys 22 in the nonwoven material 12. The created peaks and valleys 22 act as pockets to transport the SAP 16. The SAP 16 can be placed continuously (not shown) or discontinuously as shown. SAP 16 delivery methods can be by vibration, dimple drum, scheduled delivery, or any other method known in the art. Additionally, the coordination between the deposition of SAP 16 and the time and orientation of the junction of the nonwoven layer 20 can vary between a vertical drop of SAP 16 in a gap between the vertically running web 20 and the combined web 12 / 16 across the nip lines, or the SAP 16 can be deposited on web 12/16 running in the machine direction horizontally so that pockets 22 can collect SAP 16 before web 20 running in the machine direction. horizontal machine.

The dimensions of the pleats 22 are adjustable with different spacing or number of elastic threads 14. It may be desirable to vary the spacing and size of the pleats to allow for higher or lower concentrations of SAP 16 in some sections of the diaper. The level of stretch in the yarns 14 and the amount of relaxation prior to deposition of SAP 16 can also change the dimensions of the pleats 22.

In a preferred embodiment, the SAP 16 can be deposited on the nonwoven layer 12 while the web 12 is moving horizontally in the machine direction, and when the second nonwoven layer 20 is applied and engaged, the pulpless core web combined can move down in any desired way.

Referring to Figures 4a and 4b, a second non-woven layer 20 is applied over the elastic yarns 14 and the peaks and valleys 22 filled with SAP 16 in the first non-woven layer 12. As shown in Figure 5, a second The alternate tension released from the elastic threads 14 creates a continuous web of absorbent core material. The web of absorbent core can be processed as desired, for example cut and placed in a diaper chassis as individual cores, or cut and placed rotated as shown in Figure 9 on a running carrier web 24 which can be further process as desired. The second nonwoven layer 20 could alternatively be an acquisition / distribution film layer (an ADL layer). Describing a diaper provided from the outside, a preferred embodiment is a non-woven layer, a polyethylene layer, a non-woven material with a non-woven layer (core wrap), SAP, an additional non-woven material (top core wrap), an acquisition / distribution layer and a topsheet layer.

Still referring to Figures 4a and 4b, the SAP is shown deposited in areas where the elastic threads 14 reside, but external channels of elastic 14 containing or not containing SAP 16 can be created, as desired.

Figures 6 and 7 show alternative first and second embodiments of elastic yarn deposition patterns. 14 on the first nonwoven layer 12. In Figure 6, the deposition is in the cross-machine direction, and in Figure 7, the deposition is generally curved in the machine direction. The elastics 14 can be curved using curved or flared elastic deposition patterns as a method of adjusting the absorption performance, and also to improve the fit and appearance of the final diaper product. The elastic deposition also provides control over the direction of elasticity of the core.

Referring to Figure 8, a cross-sectional view of the second non-woven layer 20 applied over the elastic yarns 14 and the peaks and valleys 22 filled with SAP 16 in the first non-woven layer 12, shows a second tension released from the elastic yarns 14, in use conditions, for example, the shape of an absorbent core would be when a user wears a diaper. It is clear that roughness desirably inhibits SAP migration, for example it is beneficially used in incontinence adult products. This feature could also enhance the smooth feel of the product, but in the current art, a thick TDA is needed to provide the smooth function of the product. The peaks and valleys or pockets 22 that are formed minimize the tendency of the SAP 16 to accumulate through gravity to the crotch area, the lowest portion of the core as shown. Elastic yarns and their lamination with non-woven material in the center of the core can better immobilize the SAP in its wet stage.

The present invention may allow less expensive, lower performance elastics to be used because elastics and cores formed in this way can maintain a shape at body temperature. Less expensive variations are possible, for example, lower decitex spandex, plastomers or high copolymer olefins which are semi elastic. Instead of or in addition to the traditional elastics 14 as shown, tapes or films cut into tapes or tape elements can be used to access these less expensive technologies. The present invention can also use ultrasonic bonding to couple the layers (selecting polypropylene as a blending component, for example), or ultrasonic bonding can be used to trap elastic threads.

The entire crotch area can be provided with elasticity, and when combined with a front and back elastic panel, results in a general diaper product that provides end-to-end elasticity of the diaper product if desired.

A further embodiment (not shown) is that multiple layers of the absorbent core can be used. For example, each layer can be designed for a different level of absorbency, or have different directional zones.

Additionally, a fecal barrier could be incorporated into the core concept by stretching the outer threads of the elastics 14 to a higher stretch ratio than the core threads 14, and then, when the product is allowed to recede, these Lycra threads are will lift to form a bowl or boat shape without requiring any special apparatus or additional materials.

Referring now to Figure 10, a top view (and in Figure 11, a side view is shown) of a portion of a system for producing a 12/14/16/20 absorbent core laminate. The adhesive applicator (s) 32 preferably applies adhesive to the elastic threads 14 (or to the nonwoven layer 12) and the adhesive threads 14 are brought into contact with the nonwoven layer 12 by passing the threads 14 and the nonwoven layer 12 over a roll 30. As an alternative (not shown), a thermally compatible elastic 14 may be used in the form of a strand or ribbon and ultrasonically bonded where desired.

Referring now to Figure 12, after the elastic 14 engages the base nonwoven 12, the base nonwoven 12 is preferably slightly slackened between the roller 30 and the roller 38 / nip combination. 40 to accommodate reception of SAP 16 by base nonwoven material 12 creating a small groove for SAP 16.

The stretch ratios of the elastic 14 can be varied. A higher stretch ratio could reduce the level of SAP 16 per unit of nonwoven 12 / elastic 14, but when relaxed, SAP 16 can be contained in a relatively small area to achieve a high effective concentration of SAP. On the other hand, a lower stretch ratio will increase the level of SAP per unit of nonwoven 12 / elastic 14. In this case, a higher SAP doping rate is used to achieve a high effective concentration of SAP. Desirably, a higher stretch ratio can give the composite a smoother feel and lowering the stretch ratio can also reduce manufacturing cost. By changing the stretch ratio, performance and cost balance can be easily adjusted.

A SAP distribution system 34 applies SAP 16 to the base nonwoven material 12. The incoming nonwoven top layer 20 receives adhesive from the adhesive distribution system 36, and the nonwoven top layer 20 is contacted with the combination of the base nonwoven material 12 and the elastic yarn 14 in the combination of roller 38 / nip 40 to create an absorbent core laminate 12/14/16/20 that is passed downstream for further processing as desired, by example, cutting / laying, stacking or rolling.

Referring now to Figure 13a, a bottom view of the adhesive applicator 36 is shown, which applies adhesive 43 in a pattern to the bottom of the upper nonwoven layer 20. As shown in Figure 13a, the The pattern can be substantially continuous across desired areas of the non-woven top layer 20, or as shown in Figure 13b, the adhesive 43 can be applied in a striped pattern to the non-woven top 20. It may be desirable to apply the adhesive 43 in a striped pattern to correlate the spacing of the elastic threads 14 carried by the base nonwoven material 12. Since the spacing and orientation of the elastic threads 14 carried by the base nonwoven material 12 can vary In spacing, orientation, and placement pattern, so does the adhesive pattern 43 applied to the non-woven upper 20.

Referring now to Figure 13c, there is shown a top view of a SAP delivery system 34 applying SAP 16 in a preferred arrangement of SAP lanes 16 to a base nonwoven layer 12 coupled to elastic yarns 14. The SAP 16 is received from a source such as a feed hopper as shown in Figure 12, and is passed into the voids 44 in the SAP distribution system 34 to allow the SAP 16 to be applied to the base nonwoven material. 12. A preferred SAP 16 layout pattern is lanes or stripes as shown in Figure 13c, and as shown in Figure 13d, these lanes can be intermittent SAP 16 lanes. Intermittent SAP 16 distribution is achieved, for example, by interrupting the incoming flow of SAP 16 or by removing intermittent portions of the SAP 16 flow.

By forming gathers, channels or rails in the core with SAP 16, the retention, acquisition and distribution of liquids is assisted. In an alternative embodiment, alternate or divergent patterns of SAP channels or lanes can be created by heavy and light SAP 16 distribution levels. This also improves the kernel distribution performance and allows the performance to be tailored according to the intended use. In this way, the spacing of the elastic threads 14 can be alternated with heavy SAP 16 lanes adjacent to the light SAP 16 lanes that can channel the liquid in a desired pattern.

The present invention allows the use of a thinner ADL layer because the contracted core is corrugated and can store liquid. The ADL layer can be allowed to contract with the 12/14/16/20 absorbent core laminate and the result is a fully elastic core in areas where elastification is desired.

For a higher dose of SAP 16, larger (or longer) voids 44 and higher feed rates can be used. Similarly, for a lower dose of SAP 16, smaller voids 44 and lower feed rates can be used.

Referring now to Figure 14, once SAP 16 has been applied to the base nonwoven layer 12, and the adhesive 43 has been applied in a pattern to the bottom of the upper nonwoven layer 20, the materials of the absorbent core laminate 12/14/16/20 are joined by a pressure wheel 38 which pushes the upper nonwoven material 20 carrying the adhesive 43 against the elastic threads 14. The base nonwoven material 12 is carried by the contact wheel 40. In a preferred arrangement, the peaks 46 of the splined contact wheel 40 carry a base nonwoven material 12 and elastic threads 14, and the elastic threads 14 carried by the base nonwoven material 12 come into contact with the non-woven top 20. The valleys 42 of the knurled contact wheel 40 allow the position of the SAP 16 to migrate during compression of the 12/14/16/20 absorbent core laminate materials and the coupling of the non-woven material. fabric top 20 to the hil The elastics 14. The SAP 16 accumulates in the valleys 42. As shown in Figure 15, an absorbent core laminate 12/14/16/20 is formed, with the remaining SAP 16 captured in the pockets, to create a 12/14/16/20 absorbent laminate core as shown in Figure 18.

After the 12/14/16/20 absorbent core laminate is created, the laminate is passed downstream for further processing as desired. This may include winding to create a roll 50 of 12/14/16/20 absorbent core laminate as shown in Figure 16, cutting and stacking the 12/14/16/20 absorbent core laminate as shown in Figure 17. Referring to Figure 17 in particular, there is a side view of a system for stacking a nonwoven top layer coupled to elastic yarns carried by a base nonwoven layer, the base nonwoven layer carrying SAP material to form an absorbent laminate core is shown. A stack 52 of 12/14/16/20 discrete absorbent core laminate pieces can be assembled for packaging.

Preferably, the 12/14/16/20 absorbent core laminate is cut and placed, and this cut and placement can take any shape, such as traditional cores that are variably placed in the construction of disposable products. For example, the formed 12/14/16/20 absorbent core laminate can be placed adjacent to an acquisition / distribution layer (ADL) (not shown).

The foregoing is considered only illustrative of the principles of the invention and it is not intended to limit the invention to the exact construction shown and described.

Claims (7)

1. A method of forming an absorbent core, the method comprising: providing a first layer of material (12); coupling elastic yarns (14) under tension to the first material layer (12) to form a combination of elastic and material layer; performing a first stress relief to partially relax the elastic threads (14), wherein the partial relaxation of the elastic threads (14) deforms the first material layer (12) to form a plurality of valleys in the first material layer ( 12) to capture a superabsorbent polymeric material (16); applying the superabsorbent polymeric material (16) onto the first material layer (12); Y coupling a second layer of material (20) to the combination of first layer of material and elastic. The method of claim 1, wherein the superabsorbent polymeric material (16) is applied when the first layer of material (12) moves horizontally in the machine direction. The method of claim 1, wherein applying the superabsorbent polymeric material (16) onto the first material layer (12) comprises applying the superabsorbent polymeric material (16) in a plurality of lanes defined by adjacent pairs of elastic threads. (14); Y wherein the plurality of lanes of the superabsorbent polymeric material (16) are intermittently applied to form voids in the superabsorbent polymeric material (16), which extend in the machine direction. 4. A stretchable absorbent core, comprising: a first layer of material (12); a series of elastic thread members coupled to the first material layer (12) in a partially taut state that deforms the first material layer (12) to form a plurality of valleys therein; a second material layer (20) coupled to the elongated elastic yarn members and over the first material layer (12); Y a superabsorbent polymeric material (16), located in the plurality of valleys and between the first material layer (12) and the second material layer (20), to be captured in the plurality of valleys. The stretchable absorbent core of claim 4, wherein the series of elastic yarn members comprises linear elastic yarns (14). The stretchable absorbent core of claim 4, said absorbent core being sectioned into discrete core portions. A diaper product carrying a stretchable absorbent core portion of claim 6.